To make this Hawaiian Garlic Shrimp gluten free, replace the all-purpose flour with a gluten-free flour blend, cornstarch, or a small amount of gluten-free rice flour for coating the shrimp. You should also confirm that the paprika, cayenne, butter, and any packaged seasonings are labeled gluten free, since additives and cross-contact can vary by brand. The shrimp, garlic, olive oil, lemon juice, and parsley are naturally gluten free. If cross-contact is a concern, use a clean skillet and utensils and serve the shrimp with gluten-free sides such as rice or roasted vegetables.